There is only one asphalt road on Boa Vista - from the airport to Sal Rei. There are also some paved roads between villages. Other roads do not deserve this name - they are rather small tracks, not recommended for car driving. Off-road driving is not possible because of stones. Anyway I recommend to rent a car (in Sal Rei or at the airport) to see at least Espringueira and praia de Chava. Abandoned village Curral Velho on south of the island and Cabo de Santa Maria beach on north with many wrecks of ships can be dangerous places. Roads on the southern side of Boa Vista are practically non-existent. You can reach Praia de Santa Monica by asking people in Povoacao Velha where is the "road" to the beach. You can reach Curral Velho (if you really must) turning right from the road from Rabil to Joao Galego on a gravel road around 8 kilometers after Rabil (there is a road sign Curral Velho).